U.S. patent application number 12/674738 was filed with the patent office on 2011-04-28 for pole construction for framework towers of wind power plants.
Invention is credited to Klaus Huesemann.
Application Number | 20110094180 12/674738 |
Document ID | / |
Family ID | 40280177 |
Filed Date | 2011-04-28 |
United States Patent
Application |
20110094180 |
Kind Code |
A1 |
Huesemann; Klaus |
April 28, 2011 |
POLE CONSTRUCTION FOR FRAMEWORK TOWERS OF WIND POWER PLANTS
Abstract
The invention relates to a mast structure for tower structures
of wind power installations having a height of more than 80 meters
with corner posts composed of sub-profiles, wherein the corner
posts are each formed are formed from at least two sub-profiles
comprising a sub-profile A and a sub-profile I which are not
integrally connected to one another, wherein the sub-profiles
together form a closed overall profile and separating joints of the
closed overall profile are established such that they are arranged
aligned with corresponding separating joints of closed overall
profiles of an adjacent corner post which is connected to
struts.
Inventors: |
Huesemann; Klaus; (Stemwede,
DE) |
Family ID: |
40280177 |
Appl. No.: |
12/674738 |
Filed: |
August 22, 2008 |
PCT Filed: |
August 22, 2008 |
PCT NO: |
PCT/EP08/06960 |
371 Date: |
January 11, 2011 |
Current U.S.
Class: |
52/651.01 |
Current CPC
Class: |
F05B 2250/11 20130101;
E04H 12/08 20130101; E04H 12/10 20130101; Y02E 10/728 20130101;
F05B 2240/9121 20130101; Y02E 10/72 20130101; F03D 13/20
20160501 |
Class at
Publication: |
52/651.01 |
International
Class: |
E04H 12/02 20060101
E04H012/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 23, 2007 |
DE |
10 2007 039 957.1 |
Claims
1. A mast structure for framework towers of wind power
installations having a height of more than 80 meters with corner
posts (1) which are each formed from at least two sub-profiles
comprising a sub-profile A (2) and a sub-profile I (3) which are
not integrally connected to one another, wherein the sub-profiles
together form a closed overall profile and separating joints of the
closed overall profile are established such that they are arranged
aligned with corresponding separating joints of closed overall
profiles of an adjacent corner post (1) which is connected to
struts (11), characterized in that the sub-profile I (3) is angled
in the cross section over a longitudinal edge with an angle alpha
between 50.degree. and 70.degree., preferably 60.degree., and the
sub-profile A (2) is angled in the cross section over two
longitudinal edges with an angle beta and an angle gamma, each of
60.degree. to 90.degree., preferably 75.degree., and in that the
internal contour (19) which is formed by the direct connection of
the angles alpha, beta and gamma, of the assembled overall profile
of a corner post (1) forms a triangle, and the angles alpha, beta
and gamma are between 160.degree. and 250.degree., preferably
210.degree..
2. The mast structure as claimed in claim 1, characterized in that
the sub-profile I (3) and the sub-profile A (2) have connecting
areas (7, 8, 9, 10) which are angled at angles delta for the
sub-profile I (3) and eta for the sub-profile A (2), such that the
respectively opposite connecting areas (7 and 8 as well as 9 and
10) are aligned parallel to one another, and the angle delta for
the sub-profile I (3) is between 80.degree. and 110.degree.,
preferably 97.5.degree., and the angle eta for the sub-profile A
(2) is between 80.degree. and 110.degree., preferably
97.5.degree..
3. The mast structure as claimed in claim 1, characterized in that
connecting areas (7, 8, 9, 10) for connection of the sub-profiles
have a length which corresponds to 3 to 10 times, preferably to 4
times, the material thickness of the respective sub-profile.
4. The mast structure as claimed in claim 1, characterized in that
the overall profile of a corner post (1) in the fitted state has an
approximately equal area moment of inertia about both major axes of
the overall profile.
5. The mast structure as claimed in claim 1, characterized in that
the longitudinal axes (16) meet at one point (18) on struts which
are connected at one height to an overall profile of a corner post
(1), and the center of gravity (17) of the overall profile is
located at a radius of 0 to 40 mm, preferably at a radius of 20 mm,
around the point (18).
6. The mast structure as claimed in claim 1, characterized in that
lower corner post segments (4) of the mast structure have
sub-profiles with a different material thickness than at least one
corner post segment (5) which is arranged above the lower corner
post segments (4).
7. The mast structure as claimed in claim 1, characterized in that
at least one sub-profile of the corner post structure is composed
of the fine-grain steel.
8. The mast structure as claimed in claim 1, characterized in that
the sub-profiles (2, 3) and/or the struts (12) are composed at
least partially of non-metallic materials, for example laminated
carbon fibers.
9. The mast structure as claimed in claim 1, characterized in that
the sub-profiles (2, 3) and/or the struts (12) are formed at least
partially from natural materials containing fibers.
Description
[0001] The invention relates to a mast structure for tower
structures of wind power installations having a height of more than
80 meters with corner posts composed of sub-profiles, wherein the
corner posts are each formed are formed from at least two
sub-profiles comprising a sub-profile A and a sub-profile I which
are not integrally connected to one another, wherein the
sub-profiles together form a closed overall profile and separating
joints of the closed overall profile are established such that they
are arranged aligned with corresponding separating joints of closed
overall profiles of an adjacent corner post which is connected to
struts.
[0002] Angled profiles are generally used for the corner posts of
framework tower structures. The load on the angled profiles
increases with the height of the towers and with the size of the
components mounted on the tower (for example wind power
installations). To a certain extent, these loads can be coped with
by the use of profiles with larger profile cross sections. However,
the profile cross sections cannot be enlarged indefinitely, since
production engineering constraints limit the manufacture of angled
profiles.
[0003] DE 1 882 171 U correspondingly discloses a plurality of
angled profiles being connected by welds, and a cruciform profile
for corner posts being produced in the manufacturing state itself.
This profile configuration is not optimal with respect to the
achieved area moments of inertia of the corner post structure.
[0004] DE 103 08 176 A1 accordingly proposes corner posts being
manufactured from molded steel whose profile has at least two
flanks, wherein the flanks are connected by means of a support. A
lattice tower constructed in this way offers the advantage that the
profile of the corner posts is stronger because of the provision of
an additional support. This results in corner posts whose kink
length is considerably better than that of conventional corner
posts manufactured from angled profiles.
[0005] A further possible way to produce high towers is to increase
the number of corner posts, of which there are in general four, in
order to comply with the static requirements. In this case, the
limbs, which are connected by cross-struts, of the rectangular
angled profiles which are generally used are no longer aligned
approximately, as a result of which the connection of the struts,
which fan out, is not parallel to the corresponding limbs of the
angled profiles, and this is disadvantageous.
[0006] This problem is overcome by using corner posts composed of a
plurality of sub-profiles, in general up to a total of four, thus
increasing the cross-sectional area of the corner posts. However,
this structural solution still comprises a structure with four
corner posts.
[0007] One disadvantage is that the inertia radii, which are
important for kink stability are very small since a large
proportion of the cross-sectional area of the corner posts is
located in the center of gravity area.
[0008] Many intermediate supports for the corner posts by means of
struts are accordingly required, thus considerably increasing the
design complexity.
[0009] Because of these problems, structures exist for framework
towers in which corner posts and the fanning-out are formed from
tubes. In this case, the material is concentrated in the profile of
the corner posts and in the profile of the fanned-out areas in a
statically optimum arrangement, well away from the neutral fiber of
the profile. However, the connections of the fanned-out areas and
the abutments of the corner posts in structures such as these are
generally produced by welding processes. Welded connections are
complex to manufacture.
[0010] Furthermore, weld beads have a high notch effect, which
means that they must be overdesigned to a major extent, and are
therefore virtually impossible to use, for dynamically loaded
towers such as wind power installations.
[0011] Particularly against the background of new generations of
wind power installations, whose hub heights are more than 80 meters
and/or whose power is more than 2 Megawatts, new approaches have
been developed for the design of the framework structure, because
of the high static and dynamic loads on the tower structures.
[0012] EP 1 442 807 explains a corner-post profile which is
optimized for use of material and assembly. In this case, a
commercially available I-profile, which has a center web and
flanges, and which profile is referred to in the specialist world
by the expression "Peiner Traeger", is changed to a new shape after
the rolling process for profile production, such that an angle of
90.degree. is included between the flanges. The new profile
produced in this way may in this case be open or closed. In the
latter case, the flanges are welded to one another on the contact
line.
[0013] This manufacture of the new profiles corresponding to EP 1
442 807 is complex, since a further manufacturing process is
required after the rolling of the I-profile.
[0014] The advantage of the abovementioned structure over angled
profiles is the large cross-sectional area which can be achieved
with just one profile, and the inertia radius, which is greater
than that of angled structures. The disadvantages are that the
inertia radius is considerably less than that of a comparable tube
(for example by a factor of 1.4), and that struts of the corner
posts do not introduce the forces in the direction of the center of
gravity of the profile, as a result of which the corner posts are
twisted.
[0015] Another approach to produce corner posts with a closed
profile is represented by the use, as disclosed in DE 102005012817
A1, of an octagonal profile which comprises two open
sub-profiles--and is closed in the assembled state. The cross
section of the assembled profile virtually corresponds to that of a
tube. The sub-profiles are screwed. The struts are fitted by means
of metal connecting sheets between the sub-profiles, such that
forces that occur are introduced by the struts virtually centrally
into the corner post which is formed by the screwed sub-profiles.
The fitting of the metal connecting sheets results in a gap between
the screwed sub-profiles. In order to ensure that the static
characteristics of the assembled profile correspond to a closed
profile, further screw connections may therefore be required, inter
alia, on the sub-profiles between the struts. A spacing element is
arranged on these additional screw connections between the
sub-profiles, and is referred to as a tie plate. The required
distance between the additional screw connections and therefore the
number of tie plates required depends on the kink robustness of the
profile halves with the reduced area moment of inertia.
[0016] Furthermore, the geometric conditions relating to the
connection of the struts mean that the approximation of the
corner-post profile to the statically advantageous tubular shape
leads to sub-profiles with a very different area moment of
inertia.
[0017] For example, in the case of a tower with four corner posts
with the abovementioned structure, this results in an angle of
about 270.degree. for the outer metal sheet of the corner post. The
corresponding result for the inner metal sheet is an angle of about
90.degree.. This results in the inner metal sheet having a lower
area moment of inertia than the outer metal sheet, thus resulting
in a considerable number of additional screw connections and tie
plates between the strut connections. Since the screw connections
must be regularly checked, this results in corresponding costs,
which depend on the number of tie plates that are used.
[0018] During the production of the profiles, it has also been
found that it is complex, from the production engineering point of
view, to manufacture closed octagonal profiles.
[0019] The object of the invention is to provide a structure of a
corner post of a lattice mast in which the forces which are
transmitted by the connected struts are introduced virtually
centrally into the corner post, and wherein the corner post has a
virtually identical area moment of inertia about both major axes,
and the structure is simpler to manufacture than a structure
composed of octagonal corner-post profiles, and in which the number
of tie plates required between the sub-profiles of a corner post is
minimized in comparison to the solution disclosed in DE
102005012817, and/or the material consumed for the corner posts of
lattice mast structures is reduced.
[0020] The object is achieved by the mast structure having the
features of claim 1. Advantageous refinements are described in the
dependent claims.
[0021] For optimum use of material for the design configuration of
overall profiles, it is of central importance that the forces
transmitted by the struts be introduced centrally into the corner
post and also that the minimum area moment of inertia of the
overall profile be maximized. For closed overall profiles formed
from sub-profiles, the minimum area moment of inertia of the
overall profile is the fundamental principle for the dimensions.
The sub-profiles likewise each have a maximum and a minimum area
moment of inertia.
[0022] The fundamental idea of the solution is to use at least one
sub-profile A and one sub-profile I for the structure of a corner
post of a lattice mast, which, when assembled to form an overall
profile, form a corner-post segment, and wherein an internal
contour, which is formed by the connection of the three inner
corner points of the overall profile, is virtually triangular in
shape, and the external contour of the overall profile has
connecting areas for metal connecting sheets, to which struts of
the lattice masts are attached.
[0023] Surprisingly, the inertia radius and the kink robustness of
a geometric cross section of the overall profile correspond
approximately to those of a tube with the same cross-sectional area
which, as is known, offers the possible optimum of kink robustness.
The high level of robustness of the overall profile results inter
alia substantially from the stiffening effect of the virtually
rectangular angled connecting areas of the sub-profiles.
Furthermore, the specific shape of the sub-profile I optimizes the
minimum moment of inertia of the major axes of the profile.
[0024] The invention will be explained in more detail in the
following text with reference to one particularly preferred
embodiment of the invention, with the following drawings being
attached for explanation:
[0025] FIG. 1: shows a partial section view of an overall profile
with metal connecting sheets and struts;
[0026] FIG. 2 shows a horizontal section through a tower structure
with eight corner posts (schematically);
[0027] FIG. 3 shows a vertical arrangement of corner-post segments
of a corner post which comprise overall profiles;
[0028] FIG. 4 shows an exemplary embodiment of an overall profile
with a sub-profile A and a sub-profile I with connecting areas;
[0029] FIG. 5 shows a view of the overall profile with the internal
contour of a triangle, which connects the angles alpha, beta and
gamma.
[0030] FIG. 1 shows an overall profile of a corner post 1 which is
formed from a first sub-profile I 3 and a second sub-profile A 2,
which are connected to one another in a non-integral form, for
example by screw connections or rivets. As can be seen, the first
sub-profile I 3 is angled once in the center piece, approximately
in the center, over one longitudinal edge, and has connecting areas
8, 9 which are likewise angled, at the free ends, when seen in
cross section.
[0031] The second sub-profile A 2 is angled twice in the center
piece, that is to say over two longitudinal edges, and likewise has
angled connecting areas 7, 10 on the mutually opposite free end
edges.
[0032] Metal connecting sheets 11 for struts 12 are fitted in the
junction points of the sub-profiles 2, 3 between the
joined-together connecting areas 7, 8 and 9, 10, and connect the
closed overall profiles of adjacent corner posts 1 to one another
in order in this way to produce a framework tower structure.
[0033] In the exemplary embodiment according to the invention shown
in FIG. 2, the lattice mast has eight corner posts. In the
longitudinal direction, these corner posts comprise sub-profiles
which are each formed from two preferably angled metal sheets. When
the sub-profile I 3 is assembled with the sub-profile A 2, the
overall profile created in this way has a cross section which
corresponds virtually to that of a triangle, as can be seen in FIG.
5.
[0034] The structure is assembled by screw connections, preferably
at the building site. In order to ensure accessibility to the screw
connection on the profile hardness, hand holes which are not shown
are provided in the sub-profiles. In general, these is therefore no
need for any welding work.
[0035] For production-engineering reasons, particularly because of
joined areas during the process of edging the sub-profile I 3, it
is generally advantageous to make the angle alpha greater than
60.degree..
[0036] FIG. 2 shows the structure of a lattice mast with eight
corner posts 1, and with the lattice mast having a height of 120
meters. A wind turbine with a power of 2 MW is intended to be
arranged on the lattice mast.
[0037] FIG. 3 shows a vertical arrangement of corner-post segments
4, 5, which are composed of overall profiles, of a corner post 1,
wherein an upper segment 5 has a smaller cross section than a lower
segment 4. The corner-post segments 4, 5 are connected to one
another by means of butt plates 13, 15. In order to allow a
force-fitting connection to be produced, for example by screw
connections or riveting, distances between the vertically arranged
overall profiles, which are screwed to butt plates 13, 14, can be
compensated for by means of filler plates 15, which are placed
between a corner-post segment 4, 5 and a butt plate 13, 14.
[0038] Tie plates 11b can be arranged on the connection between the
sub-profiles.
[0039] An overall profile as shown in FIG. 4 is used in the central
height segment of the tower structure. The material used for the
overall profiles is a Quality S 355 construction steel with a
length of 12 meters and a material thickness of 14 millimeters. A
profile height H of 497 millimeters and a profile width B of 459.6
millimeters results in the following area moments of inertia for
the profiles according to the invention:
Sub-profile I
[0040] max=224438000 mm.sup.4 [0041] min=67437500 mm.sup.4
Sub-profile A
[0041] [0042] max=594600000 mm.sup.4 [0043] min=204187000
mm.sup.4
Overall Profile
[0043] [0044] max=825446000 mm.sup.4 [0045] min=819038000
mm.sup.4
[0046] In this case, the sub-profile I 3 has an angle alpha of
60.degree.. The sub-profile A 2 has two angles beta and gamma of
75.degree. each. The connecting areas of the sub-profiles 7, 8, 9,
10 are angled approximately at right angles, as a result of which
the respectively opposite connecting areas 7 and 8 as well as 9 and
10 are aligned parallel to one another.
[0047] The angled connecting areas have a length which on the one
hand allows assembly of the connecting pieces and on the other hand
is designed to ensure the necessary stiffening of the profile.
[0048] The center of gravity 17 of the area moment of inertia is
16.93 mm above the intersection of the lines of symmetry 16.
[0049] One particularly advantageous aspect of this structure is
that it results in the corner post having a virtually closed
profile in the assembled state, with the area moments of inertia of
the major axes being virtually identical.
[0050] The struts are connected to the overall profile via metal
connecting sheets 11, which are arranged between the sub-profiles
of the overall profile. The introduction of force, which is thus
directed toward the center of the corner post, reduces bending
moments and torsions on the corner posts in comparison to
conventional corner-post structures, such as corner-post structures
composed of angled iron.
[0051] The fitting of the metal connecting sheets 11 to the
connection of the struts 12 results in a gap between the
screw-connected sub-profiles.
[0052] In order to ensure that the static characteristics of the
assembled profile correspond to those of a closed profile, further
screw connection may, inter alia, therefore possibly also be
required for the sub-profiles between the struts. Tie plates 11b
are arranged at the additional screw connections between the
sub-profiles.
[0053] The required distance between the additional screw
connections and therefore the number of tie plates 11b required are
less than in the case of corner-post structures composed of
octagonal sub-profiles.
[0054] The overall profiles of the corner post form corner-post
segments 4, 5. The corner-post segments 4, 5 are arranged in the
vertical direction with respect to one another, and are connected
by means of butt plates 13, 14. In general, the static and dynamic
loads in higher segments of tower structures are lower than in
lower segments of tower structures. One particularly advantageous
refinement of the overall profiles is obtained by varying the
material thickness and/or by varying the profile geometry, such as
the width and the height of the triangular cross section of the
overall profile. This makes it possible to minimize the amount of
material consumed for the profile. In particular, in this context,
the use of fine-grain construction steel is advantageous, since
sub-profiles can in each case be manufactured from this steel
exactly to match the static requirements.
[0055] This optimization in general results in higher segments of
tower structures designed according to the invention having a
smaller overall profile cross section than those in the lower
segments. If this results in distances between the vertically
arranged overall profiles which are screwed to butt plates 13, 14,
filler plates 15 can be used, in order to allow a force-fitting
connection, for example by screw connection.
[0056] According to the invention, the material thickness of lower
corner-post segments is also less than the material thickness of
upper corner-post segments. This is dependent, for example, on the
respective spreading of the corner posts.
[0057] In a further advantageous refinement of the invention, at
least some of the profiles are manufactured from non-metallic
materials, for example laminated carbon fibers, in order to achieve
weight savings and/or to reduce the material consumption of
metallic construction materials.
* * * * *